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Organic Molecular Tracers in the Atmospheric Aerosols from Lumbini, Nepal, in the Northern Indo-Gangetic Plain: Influence of Biomass Burninghttp://lib.icimod.org/record/32871
Wan, X.;
Kang, S.;
Li, Q.;
Rupakheti, D.;
Zhang, Q.;
Guo, J.;
Chen, P.;
Tripathee, L.;
Rupakheti, M.;
Panday, A. K.;
Wang, W.;
Kawamura, K.;
Gao, S.;
Wu, G.;
Cong, Z.;
To better understand the characteristics of biomass burning in the northern Indo-Gangetic Plain (IGP), total suspended particles were collected in a rural site, Lumbini, Nepal, during April 2013 to March 2014 and analyzed for the biomass burning tracers (i.e., levoglucosan, mannosan, vanillic acid). The annual average concentration of levoglucosan was 734 ± 1043 ng m−3 with the maximum seasonal mean concentration during post-monsoon season (2206 ± 1753 ng m−3), followed by winter (1161 ± 1347 ng m−3), pre-monsoon (771 ± 524 ng m−3) and minimum concentration during monsoon season (212 ± 279 ng m−3). The other biomass burning tracers (mannosan, galactosan, p-hydroxybenzoic acid, vanillic acid, syringic acid and dehydroabietic acid) also showed the similar seasonal variations. There were good correlations among levoglucosan, organic carbon (OC) and elemental carbon (EC), indicating significant impact of biomass burning activities on carbonaceous aerosol loading throughout the year in Lumbini area. According to the characteristic ratios, levoglucosan ∕ mannosan (lev ∕ man) and syringic acid ∕ vanillic acid (syr ∕ van), we deduced that the high abundances of biomass burning products during non-monsoon seasons were mainly caused by the burning of crop residues and hardwood while the softwood had less contribution. Based on the diagnostic tracer ratio (i.e., lev ∕ OC), the OC derived from biomass burning constituted large fraction of total OC, especially during post-monsoon season. By analyzing the MODIS fire spot product and 5-day air-mass back trajectories, we further demonstrated that organic aerosol composition was not only related to the local agricultural activities and residential biomass usage but also impacted by the regional emissions. During the post-monsoon season, the emissions from rice residue burning in western India and eastern Pakistan could impact particulate air pollution in Lumbini and surrounding regions in southern Nepal. Therefore, our finding is meaningful and has a great importance for adopting the appropriate mitigation measures, not only at the local level but also by involving different regions and nations, to reduce the biomass burning emissions in the broader IGP region nations.Kang, S.Mon, 27 Nov 2017 03:35:52 GMThttp://lib.icimod.org/record/328712017http://lib.icimod.org/record/32871
Brown Carbon in the Cryosphere: Current Knowledge and Perspectivehttp://lib.icimod.org/record/32232
Wu, G.-M.;
Cong, Z.-Y.;
Kang, S.-C.;
Kawamura, K.;
Fu, P.-Q.;
Zhang, Y.-L.;
Wan, X.;
Gao, S.-P.;
Liu, B.;
Recently, the light-absorbing organic carbon, i.e., brown carbon (BrC), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. BrC is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, BrC could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of BrC (in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic, and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of BrC like Absorption Ångström Exponent (AAE) and Mass Absorption Efficiency (MAE) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning BrC is available. Considering biomass burning as a dominant source of BrC, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of BrC merits more investigation in the future.Wu, G.-M.Mon, 05 Sep 2016 10:25:46 GMThttp://lib.icimod.org/record/322322016http://lib.icimod.org/record/32232